[In dilated cardiomyopathy normal signal-averaged electrocardiogram does not identify low mortality risk patients].

In survivors of myocardial infarction normal signal-averaged electrocardiogram (SAECG) identifies patients at low risk of death. The aim of this study was to see whether this routine, noninvasive test can also help identify low risk individuals among patients with idiopathic dilated cardiomyopathy (DCM) with markedly depressed left ventricular function. We performed time-domain SAECG using Butterworth 40-250 Hz filter in 67 DCM patients with no coronary stenoses and no bundle branch block on standard electrocardiogram (age 30 +/- 10 years, ejection fraction 35 +/- 12%) and followed them prospectively for the mean of 27 months. Ten cardiac events occurred defined as cardiac death (n = 6) or heart transplantation (n = 4). Mean fQRS, LAS, and RMS values and incidence of abnormal SAECG did not differ significantly between patients with events and event-free survivors (124 +/- 20 vs 123 +/- 17 ms; 32 +/- 10 vs 39 +/- 16 ms; 31 +/- 23 vs 27 +/- 21 mV and 3/10 (30%) vs 26/57 (46%) respectively; p = NS for all comparisons). We did not find significant difference between event-free survival curves of patients with normal and abnormal SAECG, and also of patients with fQRS > 114 ms and L 114 ms; LAS > 38 ms and L 38 ms, and of patients with RMS < 20 microV and > or = 20 microV (log-rank p = 0.4-0.6). We conclude that in patients with DCM with markedly depressed left ventricular function normal time-domain SAECG is probably not useful in identifying low risk individuals.